1. Field of the Invention
The present invention relates to a power generation amount control apparatus for use in a vehicle.
2. Description of Related Art
There is known a power generation control system which operates to stabilize the idle speed of a vehicle engine, and is configured not to perform power generation restriction control when a demand to increase power generation amount is received while the engine is in the idle state in order to prevent the output voltage of a vehicle generator driven by the vehicle engine from falling excessively, and improve response at the time when an electrical load is applied. For example, refer to Japanese Patent Application Laid-Open No. 2007-282328.
Also, there is known a power generation control system configured to restrict an excitation current of a vehicle generator driven by a vehicle engine when the rotational speed of the vehicle generator lowers while the vehicle engine is in the idle state depending on the degree of the lowering of the rotational speed in order to improve the rotation stability and the output voltage of the vehicle generator, and release the restriction of the excitation current when the rotational speed of the vehicle generator has recovered. For example, refer to Japanese Patent Application Laid-Open No. 2007-295659.
However, the conventional techniques described in the above patent documents have a problem in that the output voltage of the vehicle generator may vary and the voltage of a battery charged by the vehicle generator may increase when the power generation restriction control is performed, because the power generation control is not performed taking into account deterioration of the battery or the vehicle generator. For example, when the battery has been deteriorated and the internal resistance thereof has increased excessively, the battery voltage drops extremely when the power generation restriction control is performed, because the battery is in the insufficiently charged state even if the battery has been charged. Further, since the generator torque to generate a certain output current when the vehicle generator is deteriorated is increased compared to that when the vehicle generator is not deteriorated, there may occur a case in which the idle speed cannot be stabilized even when the power generation restriction control is performed, because the power generation restriction control is performed without taking into account this increase of the generator torque, and accordingly reduction of the generator torque by the power generation restriction control may be insufficient to prevent engine speed variation (hunting) from occurring.
As explained above, it is difficult to ensure the idle speed stability and output voltage stability by the conventional power generation control in which deterioration of the battery and the generator are not taken into account.